Interactions between fluids and solids can be studied by recording the mass and/or composition of a fluid as a function of time. In the fields of adsorption and capillary condensation, a method wherein the mass of the fluid indicates the phase of the fluid is broadly termed as “gravimetric.”
Gravimetric apparatuses are superior to other methods of measurement because they use high-precision balances to measure the mass of a fluid in real time. The use of high-precision balances negates the possibility of incurring errors through equation-of-state mass calculations, which are inherent to other methods, and allows for an understanding of the kinetics of adsorption, desorption, and capillary condensation. Furthermore, gravimetric apparatuses may be compatible with extreme temperatures and pressures and may be used for flow-through measurements, capabilities that are extremely difficult, if not impossible, to achieve with other types of apparatuses.
Apparatuses that study adsorption, desorption, and capillary condensation by using the gravimetric method are known in the art, and commercial gravimetric apparatuses can be purchased from vendors. These apparatuses and their use in gravimetric methods are described in Gor et al., 2013; Russo, Ribeiro Carrott, & Carrott, 2012; Russo et al., 2012; Qiao, Bhatia, & Nicholson, 2004; Shim, Lee, & Moon, 2006; http://www.rubotherm.com/rubotherm-gmbh-en.html
The apparatuses known in the art are not geared towards the petroleum industry. These apparatuses use microbalances or magnetic suspension balances, can only accommodate small solid substance quantities (i.e., a few milligrams to a few grams), and cannot accommodate a true core holder. As such, measurements of reservoir fluids in reservoir cores at reservoir conditions cannot be performed using the apparatuses known in the art.